Shear (pin) frustration

[GlennT]

I have been working on a fencing project using my Leinbach 7300 post-hole-digger. It's been a bit difficult because our property includes areas of caliche and limestone, as well as grey clay, blue clay and red clay. And of course there are random rocks and roots that have to be chopped out with an iron bar. Anyway, I go through shear pins and ran out. My instruction manual tells me to use grade-two bolts. So, off to ACE Hardware, where the friendly clerk tells me that all of their bolts are grade-one because of the number one on the head (one of the three marks designating a grade-five bolt). Next stop: the John Deere dealer where I'm told that they also only carry grade-five or higher (grade-eight) and that this is recommended for all of their implements. Yes, well, thank you, I'll think about it. Finally I wound up at a lumber yard where they carry bolts without markings--probably grade-two, possibly grade-three. The clerks cheerfully admit that they don't have the foggiest notion as the grades of their bolts. Holy Smoke!! I hadn't realized that bolt-grade information is so esoteric--especially when you're in the business!! Sometimes I feel that we're living out in the middle of the Sahara Desert!! I suppose I could substitute a grade-five 5/16 inch bolt for the grade-two 3/8 inch bolt which is specified, but I prefer using the correct item if possible and a smaller bolt would probably chew up the holes in the universal joint somewhat. Maybe a grade-five bolt would work OK, but I don't like to abuse my equipment. Anyway, I wound up with the proper grade bolts, but it took some time and certainly required patience. Aren't people interesting?

 

[RobertN]

Isn't it fun! One of those grade-5 bolts would be like replacing a 10A fuse with a 20A fuse... I have heard too, that there is questions about the reliability of grading on import nuts and bolts, that many do not meet quality standards.

Fortunately, I still have connections with vendors that supplied my old place of work. They specialize in fasteners. Only problem is, they sell in boxes of 100 pieces minimum. Of course, that might make a 5 years supply of shear bolts...

 

[deepsnow]

This last "Spring" was an excercise in shear (pin) frustration. While snowblowing(& rockblowing )20" of late season heavy snow that nicely covered a few baseball size frost heaved stones I sheared not only the auger pins but the PTO shaft pin. Reaching in to my paper bag containing the spare pins, no auger pins left. After spending another +1hour clearing a path with FEL & 3pt blade it was another hour (round trip) to my NH dealer for pins. Lucky for me he has an isle of bins containing every bolt nut for any need. Glen, hope never to experience your shear (pin) frustration.

 

[icat]

Have the same soil on my place out in Yoakum - not too far from yours. My dealer tried to convince me that a sheer pin rotary cutter would be just fine, but I decided to go the extra bucks and get the slip clutch. I'm one of those people who hate running out of pins, bolts, nuts, etc. So I'd probably have stocked up on the sheer pins at the dealer (heck - I bought 4 cans of Kubota Orange and 2 of Grey). Your experience with the post hole digger makes me feel like I made the right choice!

On a similar note, went to three different stores in Victoria looking for nail gun nails in 3". Only Lowes had the nails, but some yahoo had pilfered about a third of the box! /forums/images/graemlins/mad.gif

Other than the sheer pin issue, how do you like the digger? Is it going deep enough (I'm assuming your doing fence lines)?

 

[Anonymous Poster]

For the most part your local hardware stores or lumber yards have no idea what grade bolts they buy. They are just buying a low carbon bolt which has several different grades (including numered and lettered). Typically they are buying from distributors who get them from a variety of off-shore manufacturer's. None of the low carbon content bolts are required to have any markings on the head. You will probably be OK with any of the hardware store, unmarked head bolts for shear pins on your post hole digger.

I remember shearing 3 or 4 bolts on some holes when I was putting my fence in. Got pretty good and fast (<1 minute) at replacing the busted bolt.

Good luck with your project.

Jeff

 

[jinman]

If you have a Tractor Supply close to Fredericksburg, they carry lots of grade 2 bolts (no marks on the head). I buy a dozen at a time and keep them handy. Of course, my auger and my rotary cutter used different sizes of bolts, so I also bought a container to store my bolts in. Even so, it always seems like you will run out at the worst possible time. It just Murphy's law at work. /forums/images/graemlins/crazy.gif

 

[MikePA]

Last Fall, when I was digging 184 post hole, I would buy a dozen at a time from my local TruValue hardware store. I made several trips, so I decided to buy a box of 100 bolts and nuts. Didn't break another shear bolt after that. /forums/images/graemlins/cool.gif

Since many of the holes will need re-dug, (didn't have time to get posts in before winter) I should be all set! /forums/images/graemlins/grin.gif

 

[40Kchicks]

All this shear frustration really makes me appreciate my hydraulic post hole digger. I've dug lots of hole with lots of rocks with no frustration.
Eric

 

[jrlichina]

Bolt grades are sometimes difficult to determine if you do not have the manufactures box. In GENERAL bolts with no markings are Grade 2, each additional mark is one more. So bolt with 6 "ticks" on the head is a Grade 8. I've attached a link the denotes the grades. Grade Chart

 

[herbenus]

Confession: I've never worried about it. My cutter uses a metric size which is hard enough to find. When I find it I usually get 3 or 4. Never inquired about grade. I know they are not grade 8 though.

Of course now I'm curious and will check manual when I get home. My preference would be lowest grade. Maybe I'll look for some brass.

I had a farm boy tell me once that he never used shear pins. That instead he used cotter pins. Easier to install and shear at lower values. I tried it and big mistake. I could hardly get mower started before shearing pin.

 

[BillyP]

I have a tiller that uses an 8.8 grade shear pin (metric). That same 8.8 would be right at a grade 5 SAE.

 

[jinman]

So...
Does your hydraulic PHD ever get stuck or stalled? What does it do when you hit a rock? Does the hydraulic motor just stop? I suspect it's also pretty expensive. I've seen them, but never considered them to be a viable option since I don't dig postholes for a living.

 

[uhmgawa]

</font><font color="blue" class="small">( So...
Does your hydraulic PHD ever get stuck or stalled? What does it do when you hit a rock? Does the hydraulic motor just stop? I suspect it's also pretty expensive. I've seen them, but never considered them to be a viable option since I don't dig postholes for a living. )</font>

It will just stall while the relief valve hisses until you
let up on the spool. The nice thing about hydraulic augers
is they are reversible allowing you to back out of the bind
and try again without losing your seat. Some can also be
mounted on loader/backhoe buckets allowing more flexibility
compared to 3PH/PTO augers.

Worth the money if you are doing a fair number of holes
and/or in rocky/root-laden soil. But you need to get
that hydraulic power from somewhere and turn it back into
rotary motion. I wouldn't be surprised to find a net
loss of 20% or so which may be an issue for some.

 

[jinman]

</font><font color="blue" class="small">( they are reversible allowing you to back out of the bind
)</font>

Thanks for the info. That reversing feature sounds really handy.

 

[grandad]

Hi, Glenn. My wife and I just visited family in Fredericksburg, and from walking their land, I can certainly understand how you might snap a shear pin or two digging post holes down there! If fact, I'm thinking a charge of dynamite might come in handy some of the time! But, aside from that, you sure have a beautiful part of Texas to call home!

 

[GlennT]

Icat--I'm using the Leinbach 7300 with a John Deere Model 670 (16 HP PTO). That's about as minimal as you can get. I have a 9 inch auger and dig each hole 42 inches deep. That puts the head of the auger right in the top of the hole. But, OH BOY, do you have to be careful. The tractor barely has enough power to pull the auger out of the hole and I don't dare let it auger in more than 6-8 inches before before pulling it out and clearing it. Also, I don't want to put excessive stress on the tractor or the auger head. I had one horrible experience a few months ago when the auger was at full depth in clay and I could neither pull it out nor manually reverse the rotation to free it. I suspect the bit was lodged in a root or a rock. I spent an entire afternoon with a spade, clamshell digger and iron bar digging another hole alongside the auger so that I could free it. What a rotten day! I don't mean to complain, though. My Model 670 is a great all-around tractor and this kind of work is really asking a lot of it.

 

[icat]

Thanks for the reply Glenn. When we were digging holes for our foundation with my cousin-in-law's tractor (Ford 3910), his auger would literaly stop when we tried to break the surface. Had to bring in my 5.5 HP Honda two man auger to "break the crust" and get down to 36 inches. I like the idea of the tractor mounted auger, but after that day I wondered if the two man auger wasn't the best bet. I don't know if the auger bit was dull on the tractor digger, but the 2 man punched right through. With it though, you've got a maximum depth of 36" or so. I'd like to be able to go a bit deeper on occassion.